dotfiles/zshrc: pip/poetry keyring fix

I finally figured out why this annoying keyring unlock happens when
I do a pip/poetry install. Good riddance!

See: https://github.com/python-poetry/poetry/issues/1917

dotfiles/zshrc

@@ -51,6 +51,11 @@ if [[ "$OSTYPE" =~ ^linux.*$ ]]; then
     # 2023-01-03: a bit buggy on older Intel, especially in Thunderbird (even on new Intel)
     #export WLR_RENDERER=vulkan
     {%@@ endif @@%}
+
+    # 2023-02-05: tell pip/poetry not to probe for keyrings. I'm not publishing
+    # packages to pypi.org and the popup during pip/poetry install is annoying.
+    # See: https://github.com/python-poetry/poetry/issues/1917
+    export PYTHON_KEYRING_BACKEND=keyring.backends.null.Keyring
 fi
 
 # Enable asdf version manager zsh completions